Machines such as dozers, load trucks, motor graders, wheel loaders, etc., are used to perform a variety of tasks, and they may move about a work site as they move material and perform other operations at the work site. The machines may operate in an autonomous or semi-autonomous manner to perform these tasks in response to commands generated as part of a work plan for the machines. Autonomously and semi-autonomously operated machines may increase productivity and permit operation in environments that are unsuitable or undesirable for a human operator. Autonomous or semi-autonomous systems may also compensate for inexperienced human operators as well as inefficiencies associated with repetitive tasks.
As a machine performs its tasks, it may receive information and instructions from systems that are located remotely from the machine. When an interruption in a signal or communications channel or other factors prevents communication between the machine and a remote monitoring system, the machine may be configured to cease operation until communications are restored and an operator provides an appropriate start-up signal to the machine. If an interruption in a communications channel occurs with a positioning system, the machine may continue to operate by dead reckoning but only for a relatively short period of time. The operating efficiency of the machine may be closely related to the number of interruptions experienced during operation of the machine.
U.S. Pat. No. 7,522,066 discloses a system for evaluating proximity to potential hazards. The system may include a plurality of sensors that are used to determine the distance from potential hazards. If the system determines that a person is located closer to a hazard than desired, the system may stop the operation of a machine. A zone around each hazard may set a minimum distance from the hazard.
The foregoing background discussion is intended solely to aid the reader. It is not intended to limit the innovations described herein, nor to limit or expand the prior art discussed. Thus, the foregoing discussion should not be taken to indicate that any particular element of a prior system is unsuitable for use with the innovations described herein, nor is it intended to indicate that any element is essential in implementing the innovations described herein. The implementations and application of the innovations described herein are defined by the appended claims.